Shallow clone the github head version for client libs

[liyanhui1228]

An alternative for #241

[brianquinlan]

Is this really called client libs? I thought that was https://github.com/googleapis/google-api-python-client

[liyanhui1228]

It's https://github.com/googleapis/google-cloud-python actually, I just call it clientlibs for short. That one is the discovery based APIs.

[brianquinlan]

I'd structure this a bit differently to make it more readable.

def _clone_repo(self, container, repo):
 """<docstring>"""
  _, directory = self._run_command(
    container,
    "echo $(mktemp -d)"
    stderr=False,
    stdout=True,
    raise_on_failure=True)

  shallow_clone_command = ['git', 'clone', '--depth', '1', repo, directory]
  self._run_command(
    container,
    shallow_clone_command,
    stdout=False,
    stderr=True,
    raise_on_failure=True)
  return directory

def _install(self, container: docker.models.containers.Container):
if any(GITHUB_CLIENTLIBS_PREFIX in pkg for pkg in self._packages):
  # The https://github.com/googleapis/google-cloud-python repository is large,
  # has a large amount of history and contains many independent packages.
  # Installing packages from that repository is quite slow e.g.
  # $ time pip install git+git://...
  # <result>
  # As an optimization, if any provided package is installed from this repository,
  # it is first cloned (using --depth=1 to avoid unnecessary history) and then
  # installed from local disk e.g.
  # $ time git clone --depth=1 ... && pip install ...
  # <result>
  client_repo_directory = self._clone_repo(CLIENTLIBS_GITHUB_URL)

install_names = []
for pkg in self._packages:
  if GITHUB_CLIENTLIBS_PREFIX in pkg:
    install_subdirectory = pkg.split(GITHUB_CLIENTLIBS_PREFIX)[1]
    install_names.append(os.path.join(client_repo_directory, install_subdirectory))
  else:
    install_names.append(pkg)
command = self._build_command(['install', '-U'] + install_names)
# Rest is the same.

[liyanhui1228]

Done.

[brianquinlan]

I don't like that we can run this multiple times and every time after the first will fail. I also don't like that we don't check for failures.